In construction, most building structures include walls, ceilings, and floors that have studs spaced 16″ apart (measured from the center of each stud) or about 14.5″ apart (measured between the faces of adjacent studs). The depth of a stud in most construction is about 3.5″, and the length of a stud can vary as needed or desired. In the U.S. it is common for most walls, ceilings, and floors to employ studs that are 12″ or 16″ on center. It is also common for most walls to be about 8′ to 12′ in height, but the walls can be taller as needed or desired.
The spacing of the studs creates volumes or recesses in the walls, ceilings, and floors where objects, such as wires, cables, pipes, electrical outlet boxes, and the like are typically positioned. These objects are usually partially or entirely hidden from view, such as behind drywall, paneling, tiling, or moulding.
As the remodeling and demolition industries have grown, there is a need to be able to see or determine what type of objects are behind the walls, ceilings, and floors and the object's location within the recesses.